Forbid implicit conversions from IntPoint to FloatPoint

This is a followup from an analogous change for IntRect and FloatRect which was triggered
by some unintended conversions happening.
Since FloatPoint is not a perfect superset of IntPoint, converting from IntPoint to
FloatPoint is potentially lossy, and conversions that happen by accident hide that APIs
are not used as intended.

Behaviour has been kept where it's not obviously a mistake. Truncating or snapping to
integers is sometimes beneficial.,

Bug: 860535

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I84e72a890dbddc2a9f40bb25a000f7eec75f6ffa
Reviewed-by: Fredrik Söderquist <>
Reviewed-by: Philip Rogers <>
Commit-Queue: Daniel Bratell <>
Cr-Commit-Position: refs/heads/master@{#573675}
27 files changed